The present invention relates to the field of cut and abrasion resistant combined yarns including a metallic component, to composite yarns including such combined yarns, and to the application of air interlacing technology to the manufacture of such combined yarns.
The present invention relates to composite yarns useful in the manufacture of various types of protective garments such as cut and puncture resistant gloves, aprons, and glove liners, and in particular to composite yarns useful for the manufacture of these garments that include a metallic strand as a part of the yarn construction.
Composite yarns that include a metallic yarn component, and cut-resistant garments prepared therefrom are known in the prior art. Representative patents disclosing such yarns include U.S. Pat. Nos. 4,384,449 and 4,470,251. U.S. Pat. No. 4,777,789 describes composite yarns and gloves prepared from the yarns, in which a strand of wire is used to wrap the core yarn. The core components of these prior art composite yarns may be comprised of cut-resistant yarns, non-cut resistant yarns, fiberglass and/or a metallic strand, such as stainless steel. One or more of these components may also be used in one or more cover yarns that are wrapped around the core yarn.
It is well known in the art to manufacture such composite yarns by combining an inherently cut-resistant yarn with other strands using wrapping techniques. For example, these yarns may use a core construction comprising one or more strands that are laid in parallel relationship or, alternatively, may include a first core strand that is overwrapped with one or more additional core strands. These composite yarns can be knit on standard glove-making machines with the choice of machine being dependent, in part, on the yarn size.
Wrapping techniques are expensive because they are relatively slow and often require that separate wrapping steps be made on separate machines with intermediate. wind up steps. Further, those techniques require an increased amount of yarn per unit length of finished product depending on the number of turns per inch used in the wrap. Generally, the greater the number of turns per inch, the greater the expense associated with making the composite yarn. When the yarn being wrapped is high performance fiber, this cost may be high.
Knitted gloves constructed using a relatively high percentage of high performance fibers do not exhibit a soft hand and tend to be stiff. This characteristic is believed to result from the inherent stiffness of the high performance fibers. It follows that the tactile response and feedback for the wearer is reduced. Because these gloves typically are used in meat-cutting operations around sharp blades, it would be desirable to maximize these qualities in a cut-resistant glove.
The use of a stainless steel or other wire strand, as at least a part of the core yarn, provides enhanced cut resistance in garments, such as gloves. However, various disadvantages of prior art composite yarns incorporating a stainless steel or other wire strand have been noted. For example, there has been, with prior art yarn construction techniques, a risk of breakage of some of the wire strands, resulting in exposed wire ends that can penetrate the user""s skin.
Also, during knitting, the wire component of the yarn tends to kink and form knots when subjected to the forces normally incurred during knitting. Wire strands alone cannot be knitted for this reason. While the problem is somewhat lessened by combining the wire strand or strands with other fibers as taught in the prior art, the wire component still tends to kink, knot or break, thereby lessening its usefulness in cut-resistant garments.
Thus, there is still a need for a composite yarn that includes a wire component that does not significantly kink and form knots during knitting. There is also a need for a less expensive and time consuming technique for combining cut-resistant and non-cut-resistant yarn strands with wire strands to create a single combined strand, and for the resultant yarns and garments manufactured therefrom.
In accordance with the present invention, it has been found that stretch-resistant composite yarns that include a wire component can be produced by incorporating or xe2x80x9cencasingxe2x80x9d one or more metallic strands into a strand produced by intermittently air interlacing two or more non-metallic fiber strands, at least one of the strands being of a cut resistant material that is xe2x80x9cstrongerxe2x80x9d than the wire strand having a higher tenacity and a greater resistance to stretching. Combining this stronger cut-resistant strand with the wire strand prevents kinking and forming of knots in the wire strand during knitting, thereby providing a yarn with the desired advantages of wire strands, without the disadvantages previously experienced.
The other strand used in construction of the yarn may be a cut resistant material, a non-cut resistant material and/or fiberglass. At least one of the fiber strands is a multifilament strand. The resulting combined yarn is useful alone or with other yarns in manufacturing garments, such as gloves that have surprising softness, hand and tactile response, without kinks or knots due to stretching of the wire component during garment manufacture.
The invention further relates to a method of making cut resistant combined yarns including the steps of feeding a plurality of yarn strands into a yarn air texturizing device strands to form attachment points intermittently along the lengths of the non-metallic strands, wherein the plurality of strands includes
(i) at least one wire strand;
(ii) a first non-metallic fiber strand comprised of an inherently cut resistant material; and
(iii) at least one additional non-metallic strand comprised of an inherently cut resistant material, a non-cut resistant material or fiberglass, at least one of the non-metallic fiber strands being a multifilament strand.
The first and additional non-metallic fiber strands may be identical, i.e., both or all strands may be multifilament strands of a cut resistant material. Alternatively, the cut resistant strand can be combined with a non-cut resistant strand, with one of the stands being a multifilament strand, and the other strand being a spun yarn.
The wire strand will normally be a monofilament, e.g., a single wire. During air interlacing, the non-metallic yarn fibers are whipped about by the air jet entangling the fibers of the two non-metallic yarns, and forming attachment areas, points or nodes along the length of the wire. During air interlacing, the individual fibers of the two non-metallic strands are interlaced with each other around the stainless steel strand, which is normally a single filament, encasing or incorporating the stainless steel strand within the interlaced non-metallic strands, at least in some of the zones. At other times the wire may be alongside the non-metallic strands, however since at times the non-metallic strands are interlaced around the wire, the term xe2x80x9caroundxe2x80x9d is appropriate and will be used hereinafter. As a result of the support provided by the entangled yarns at the intermittent attachment points, the bending capability of the wire component is significantly increased, minimizing breakage problems previously encountered.
These combined yarns can be used alone in the manufacture of items such as cut resistant garments, or can be combined in parallel with another yarn during product manufacture. Alternatively, the combined yarns may be used as a core yarn in composite yarns, with a first cover strand wrapped about the combined strands in a first direction. A second cover strand may be provided wrapped about the first cover strand in a second direction opposite that of the first cover strand.
Processes involving treatment of yarns with air jets are well-known in the prior art. Some of these treatments are used to create textured yarns. The term xe2x80x9ctexturingxe2x80x9d refers generally to a process of crimping, imparting random loops, or otherwise modifying continuous filament yarn to increase its cover, resilience, warmth, insulation, and/or moisture absorption. Further, texturing may provide a different surface texture to achieve decorative effects. Generally, this method involves leading yarn through a turbulent region of an air-jet at a rate faster than it is drawn off on the exit side of the jet, e.g., overfeeding. In one approach, the yarn structure is opened by the airjet, loops are formed therein, and the structure is closed again on exiting the jet. Some loops may be locked inside the yarn and others may be locked on the surface of the yarn depending on a variety of process conditions and the structure of the air-jet texturizing equipment used. A typical airjet texturizing devices and processes is disclosed in U.S. Pat. No. 3,972,174.
Another type of air jet treatment has been used to compact multifilament yarns to improve their processibility. Flat multifilament yarns are subjected to a number of stresses during weaving operations. These stresses can destroy interfilament cohesion and can cause filament breakages. These breakages can lead to costly broken ends. Increasing interfilament cohesion has been addressed in the past by the use of adhesives such as sizes. However, air compaction has enabled textiles processors to avoid the cost and additional processing difficulties associated with the use of sizes. The use of air compaction for high strength and non-high strength yarns is disclosed in U.S. Pat. Nos. 5,579,628 and 5,518,814. The end product of these processes typically exhibits some amount of twist.
Other prior art, such as U.S. Pat. Nos. 3,824,776; 5,434,003 and 5,763,076, and earlier patents referenced therein, describe subjecting one or more moving multifilament yarns with minimal overfeed to a transverse air jet to form spaced, entangled sections or nodes that are separated by sections of substantially unentangled filaments. This intermittent entanglement imparts coherence to the yarn, avoiding the need for twisting of the yarns. Yarns possessing these characteristics are sometimes referred to in the prior art as xe2x80x9cinterlacedxe2x80x9d yarns, and at other times as xe2x80x9centangledxe2x80x9d yarns.
While intermittent air entanglement of multifilament yarns has been used to impart yarn coherence, the application of this technology to combining yarns including a cut resistant yarn component and a wire component has not been recognized, nor has the resultant advantages and properties of combined yarns resulting from the application of this technology.
These and other aspects of the present invention will become apparent to those skilled in the art after a reading of the following description of the preferred embodiments when considered in conjunction with the drawings. It should be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one embodiment of the invention and, together with the description, serve to explain the principles of the invention.